How do I flip a sprite based on parent's rotation?

I have a thing set up, that makes the gun rotate in the direction of the cursor around the player and I want to make it so, when it's past or below a certain rotation.z value, it flips the gun's sprite. This is the code I have:

 using UnityEngine;
 
 public class Shooting : MonoBehaviour
 {
     private Camera _mainCam;
     private Vector3 _mousePos;
     public SpriteRenderer gun;
     public GameObject thisObj;
 
     private void Start()
     {
         _mainCam = GameObject.Find("Main Camera").GetComponent<Camera>();
     }
 
     private void Update()
     {
         RotatePoint();
         RotateGun();
     }
 
     void RotateGun()
     {
         if (thisObj.transform.localEulerAngles.z is < 270f or > 90f)
         {
             gun.flipY = true;
         }
         else if(thisObj.transform.localEulerAngles.z is > 270f or < 90f)
         {
             gun.flipY = false;
         }
         Debug.Log(thisObj.transform.localEulerAngles.z);
     }
     void RotatePoint()
     {
         _mousePos = _mainCam.ScreenToWorldPoint(Input.mousePosition);
         Vector3 rotation = _mousePos - transform.position;
         float rotZ = Mathf.Atan2(rotation.y, rotation.x) * Mathf.Rad2Deg;
         transform.rotation = Quaternion.Euler(0,0,rotZ);
     }
 }

And this is the hierarchy setup: I've tried using transform.rotation.z too.

Any help is much appreciated!